The System Testing
40 YEAR ACCELERATED MOISTURE/TEMPERATURE CYCLING
TESTS BY BUILDING RESEARCH ESTABLISHMENT (UK)
Cintec™ wall ties were subjected to accelerated moisture/temperature cycling to model the in situ conditions of the ties in traditional cavity construction. The tested wall tie was a standard 8mm diameter x 1 mm CHS stainless steel section in a nominal 16mm diameter drill hole. The tie had a conventional polyester sock and the standard Presstec grout was pressure injected in the usual manner. Clay facing bricks of 212mm x 100mm x 65mm size were used as the test parent material.
The test programme assumed that the in situ cavity construction would be fully saturated by rain-water at least once a year. It was established by trials that a half hour soak in a water tank, followed by a minimum of 2 days drying in an electric oven heated to 40°C(±2°C) to constant weight, would satisfactorily model in situ conditions.
Five pull out tests on the brick anchor specimens were undertaken seven days after construction, then at 10, 20, and 40 cycles of wetting/drying of the specimens. The tests were undertaken in a Universal Testing machine, calibrated to BS1610: 1985 Grade 2. A side load of 3.5N/mm² pressure was applied to the bed faces to simulate conditions of confinement of the brick in situ.
The full saturation value after 24-hour immersion of the brick in water was 17.5% compared to a water absorption of 15% achieved after the test soak period of 30 minutes. The nominal brick compressive strength was 43.3N/mm².
The test pull out values were as follows:
| Specimen No. | After 7 days cure | After 40 wetting/drying cycles |
|---|---|---|
| 1 | 10.45 | 9.10 |
| 2 | 12.23 | 11.00 |
| 3 | 10.68 | 10.00 |
| 4 | 10.45 | 12.90 |
| 5 | 10.90 | 9.79 |
| Mean | 10.94 | 10.56 |
| Coefficient of Variation% | 7.00 | 14.00 |
A one way analysis of variance showed the affect on the pull out performance was not significant. Regression analysis (linear as well as polynomial) confirmed this lack of significance.
The general conclusions were:
- The pull-out performance of the test/anchor clay brick combination would not be adversely affected in any significant manner in conditions of exposure to rain simulated in the test.
- Failure of the specimens was typically by pull-out of the steel tube, for steel strength primarily governed the capacity of the anchor.
- Pull-out performance of the anchor/brick system appeared to be directly proportional to the length of embedment.
The full report is available on request.
For test results on the following please download this file.
1. Bre Firetesting
2. Freeze Thaw Data
3. University of Australia – Newcastle Testing